Printable label comprising a clear face layer and a clear adhesive layer

ABSTRACT

An adhesive label comprises:
         a face layer, and   an adhesive layer,
 
wherein the face layer comprises semi-crystalline polymeric film, the adhesive layer consists of one or more adhesive sub-layers, a lowermost adhesive sub-layer of said adhesive sub-layers comprises transparent polymeric adhesive, the thickness of the face layer is in the range of 10 μm to 50 μm, the thickness of the adhesive layer is in the range of 8 μm to 25 μm, the thickness of the adhesive layer is smaller than 95% of the thickness of the face layer, an uppermost sub-layer of said adhesive sub-layers is in contact with the face layer, and the refractive index of the uppermost adhesive sub-layer is in the range of 80% to 98.5% of the refractive index of the semi-crystalline polymeric film.

FIELD

Some versions relate to a printable label, which comprises a clear facelayer and a clear adhesive layer. Some versions relate to a labelstock,which comprises a plurality of labels. Some versions relate to a methodfor attaching a label to an item. Some versions relate to a labeleditem.

BACKGROUND

It is known that a printed paper label may be attached to an item inorder to provide printed information about the product. The label may beattached to an item by using a labeling apparatus. The labelingapparatus may be arranged to operate at a high rate. For example, thelabeling apparatus may be arranged to attach labels to glass bottles ata rate, which is higher than 750 labels per minute. The labels may beprovided e.g. as a wound roll, which may comprise e.g. thousands oflabels.

SUMMARY

Some versions may relate to an adhesive label, which comprisessemi-crystalline polymeric film. Some versions may relate to alabelstock comprising a plurality of adhesive labels. Some versions mayrelate to a method for producing a labelstock. Some versions may relateto a method for attaching a label to an item. Some versions may relateto a labeled item.

According to an aspect, there is provided a label, which comprises:

-   -   a face layer, and    -   an adhesive layer,

wherein the face layer comprises semi-crystalline polymeric film, theadhesive layer consists of one or more adhesive sub-layers, a lowermostadhesive sub-layer of said adhesive sub-layers comprises transparentpolymeric adhesive, the thickness of the face layer is in the range of10 μm to 50 μm, the thickness of the adhesive layer is in the range of 8μm to 25 μm, the thickness of the adhesive layer is smaller than 95% ofthe thickness of the face layer, an uppermost sub-layer of said adhesivesub-layers is in contact with the face layer, and the refractive indexof the uppermost adhesive sub-layer is in the range of 80% to 98.5% ofthe refractive index of the semi-crystalline polymeric film.

According to an aspect, there is provided a labeled item comprising alabel attached to the surface of the item, said label comprising:

-   -   a face layer, and    -   an adhesive layer,

wherein the face layer comprises semi-crystalline polymeric film, theadhesive layer consists of one or more adhesive sub-layers, a lowermostadhesive sub-layer of said adhesive sub-layers comprises transparentpolymeric adhesive, the thickness of the face layer is in the range of10 μm to 50 μm, the thickness of the adhesive layer is in the range of 8μm to 25 μm, the thickness of the adhesive layer is smaller than 95% ofthickness of the face layer, an uppermost sub-layer of said adhesivesub-layers is in contact with the face layer, and the refractive indexof the uppermost adhesive sub-layer is in the range of 80% to 98.5% ofthe refractive index of the semi-crystalline polymeric film.

According to an aspect, there is provided a method for labeling items,the method comprising:

-   -   separating a label from a release liner by using peel plate,    -   moving the surface of an item in a first direction,    -   moving the label in a second direction, and    -   bringing a leading edge of the label into contact with a surface        of the item such that the angle between the first direction and        the second direction is in the range of 10° to 30°,

wherein the label comprises:

-   -   a face layer, and    -   an adhesive layer,

wherein the face layer comprises semi-crystalline polymeric film, theadhesive layer consists of one or more adhesive sub-layers, a lowermostadhesive sub-layer of said adhesive sub-layers comprises transparentpolymeric adhesive, the thickness of the face layer is in the range of10 μm to 50 μm, the thickness of the adhesive layer is in the range of 8μm to 25 μm, and the thickness of the adhesive layer is smaller than 95%of thickness of the face layer.

The life cycle of the above-mentioned label containing thesemi-crystalline polymeric film may include e.g. manufacturing, storing,transportation, labeling, and recycling of waste material. By using thelabel, the total costs associated with the whole life cycle of the labelmay be reduced. Using the label may provide a cost-efficient way forimproving the visual appearance of an item. Using the label may providea cost-efficient way for altering the visual appearance of an item.Using the label may provide a cost-efficient way for adding a marking toan item. Using the label may provide a cost-efficient alternative forprinting directly on the surface on an item. Using the label may allowless frequent change of rolls for a labeling apparatus, as a single rollmay comprise an increased number of labels. Using the label may befacilitate transportation of a large amount of labels. Using the labelmay be facilitate storing a large amount of label. Producing thelabelstock may consume materials. When using the label, the amount ofraw materials needed for the production may be substantially reduced.Using the label may be environmentally friendly.

High Speed Labeling

Using the label may facilitate high speed labeling, wherein the rate oflabeling may be e.g. higher than or equal to 750 labels per minute. Forexample, a labeling apparatus may be arranged to attach labels to morethan 750 glass bottles per minute.

The polymeric face layer of the label may be oriented by uniaxial orbiaxial stretching during manufacturing of the polymericsemi-crystalline film. The uniaxially or biaxially oriented face layermay be dimensionally stable. The dimensional stability may facilitateaccurate positioning of the labels during high speed labeling.

When using the stretched polymeric material, the relative stiffness ofthe face layer may also increase with decreasing thickness of the facelayer. The stiffness may be proportional to the second moment of areamultiplied by the tensile modulus. The relative stiffness of the facelayer may be proportional to the stiffness of the face layer divided bythe thickness of the face layer. The stiffness of the label mayfacilitate dispensing. The stiffness of the label may facilitateseparation of leading edge of the label from a release layer during thedispensing. The stiffness of the label may facilitate handling of thelabel when it is separated from the release layer. Thus, the uniaxiallyor biaxially oriented face layer may facilitate use of the labels forhigh speed labeling.

Visual Appearance

The label may comprise a transparent portion. For example, more than 20%of the (one-sided) area of the label may be transparent, and theremaining area of the label may comprise one or more printed markings.The original surface of an item may be observed visually through thelabel, after the label has been attached to said original surface. Theoriginal surface may form a visual background for the markings of thelabel. The original surface may highlight the markings of the label.Using the markings together with the background may improve the visualappearance of the labeled item. The markings may be associated with atrade mark and/or brand. Combining the markings of the label with theoriginal surface of the item may emphasize the visual appearance of thebrand. A potential customer may simultaneously see the marking and thetexture of the original surface of the item through the clear portion ofthe label. Combining the marking of the label with the original surfaceof the item may emphasize the association formed between the marking andthe item.

The dimensionally stable face layer may allow precision printing andaccurate positioning of the label with respect to the labelled item. Thedimensionally stable face layer may allow accurate positioning of themarking with respect to the label. The dimensionally stable face layermay allow accurate positioning of the label with respect to the item.The dimensionally stable face layer may allow accurate positioning ofthe marking of the label with respect to the item.

The label may comprise two or more layers, wherein each layer may have adifferent function. Each layer may have its own optical properties. Thevisual appearance of the label may depend on the optical characteristicsof the layers of the label. In particular, the visual detectability ofthe label may depend on the optical characteristics of the layers of thelabel.

The optical properties of the label may be tailored by selecting theoptical properties of the structural layers of the label. The opticalproperties of the label may depend on the optical properties of thestructural layers in the visible spectrum of light. The visible spectrummay refer to the wavelength range from 380 nm to 760 nm.

The refractive index of the face layer may be increased by usinguniaxially or biaxially oriented polymeric semi-crystalline film.Consequently, the upper surface of the face layer may provide moreintense optical reflections. In particular, the label may provide a highgloss effect.

The label may provide a “no-label look”, i.e. the label and thebackground may be combined such that the color and the texture of thebackground is visible through the transparent portion of the label.

The transparent portion of the label may allow substantial freedom toselect the shape and position of the marking with respect to thebackground. Using the label may provide a cost-effective solution e.g.when compared with a printed marking, which would be directly printed onthe surface of the item.

The shape of the perimeter of a printed region of the label may besubstantially different from the shape of the perimeter of the label.For example, the label may be substantially rectangular, wherein theprinted region may be e.g. circular, oval, triangular, diagonal and/orslanted. For example, the label may be substantially oval or circular,wherein the printed region may be substantially rectangular. The printedregion of the label may comprise e.g. a square, circular or irregulargraphical pattern surrounded by a clear portion of the label.

The small thickness of the label may improve the transparency of thelabel. The small thickness may reduce absorption and scattering in theface layer and in the adhesive layer. The small thickness of the labelmay make the edges of the label less discernible, by reducing scatteringof light from the edges when the label has been attached on the surfaceof the item.

In an embodiment, the total thickness of the label may be so small thatthe edge of the label is less discernible when viewed by bare eyes. Forexample, the total thickness of the label may be smaller than 38 μm (1.5mils), or even smaller than 25 μM (1.0 mils).

The label may merge visually into the background provided by the surfaceof the item. The properties of the label may be selected such that itmay be rather difficult to visually detect the clear portions of thelabel when the label has been attached on the surface of the item.

Smoothing Effect

The clear portion of the label may have a capability to hide visuallydetectable irregularities and/or scratches of the surface of the item.Attaching the label to the item may improve the visual appearance of theitem. For example, the adhesive layer may fill imperfections of thesurface of the item, wherein the high refractive index of the adhesivelayer may reduce optical scattering from the irregularities and/orscratches of the surface of the item.

The face layer and the adhesive layer may be easily bent to conform tocylindrically curved surfaces, e.g. to the surface of a typical glassbottle. The label may conform to the principal radius of curvature ofthe surface of the item. Consequently, the edges of the label may remainsubstantially unnoticeable. The thin label may cover the surface of theitem so that the edges of the label protrude very little from thesurface of the item. The low elevation of the edges of the label and thehigh dimensional stability of the face layer may reduce the risk ofdamaging the label during handling of a labeled item.

Controlling the Size of Air Bubbles

Using the thin labels in high speed labeling may sometimes causetrapping of air bubbles between the labels and the items. The airbubbles may be caused e.g. by a high-speed release behavior of theadhesive layer, when the adhesive label is separated from the linerduring the labelling process. Rapid separation of the adhesive layerfrom the release layer during high speed labeling may temporarilyincrease the roughness of the exposed adhesive layer. The time delaybetween peeling and contact with the item may be so short that air maybe carried to the interface by the irregularities of the exposedadhesive layer. When the adhesive layer is peeled away from the releaselayer at high speed, the exposed surface of the adhesive layer mayremain slightly irregular so that the adhesive layer does not have timeto smoothen before being attached on the substrate surface.Consequently, one or more air bubbles may be formed due to air trappedbetween the label and the substrate surface.

The adhesive of the label may cover the surface of the item by wetting.The wetting may ensure that the label is firmly attached to the surfaceof the item. The wetting may also (slowly) move air beneath the label sothat microscopic air bubbles coalesce to form visually detectable largerair bubbles. The wetting may be arranged to eliminate gas bubbles, bycausing overpressure and diffusion of the gas away from the bubbles.Temporal behavior of air bubbles may be controlled by selecting thematerials and the dimensions of the label. The materials and thedimensions of the label may be selected such that small air bubblestrapped between the label and the item may substantially disappear e.g.within 24 hours.

An air cushion may be formed due to the rapid movement of the label sothat air is entrained to the space beneath the label. The labeling speedmay be so high that the air does not have time to escape from the gapbetween the label and the item. The dispensing geometry may be selectedto minimize the effect of the air cushion. The dimensional stability ofthe label may be utilized when reducing the amount of air trappedbetween the label and an item. The dimensional stability of the labelmay substantially prevent formation of large air bubbles during thedispensing, when using a suitable dispensing geometry. Formation of airbubbles may be controlled by selecting the dispensing parameters.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following examples, several variations will be described in moredetail with reference to the appended drawings, in which

FIG. 1a shows, by way of example, in a cross-sectional view, a label,which comprises a face layer, an adhesive layer consisting of twoadhesive sublayers, and a printed region between the face layer and theadhesive layer,

FIG. 1b shows, by way of example, in a cross-sectional view, a label,which comprises a face layer, and an adhesive layer consisting of oneadhesive sublayer, and a printed region between the face layer and theadhesive layer.

FIG. 1c shows, by way of example, in a cross-sectional view, a label,which comprises a face layer and an adhesive layer, wherein a printedregion has been formed on the upper surface of the face layer,

FIG. 2a shows, by way of example, in a three dimensional view, attachinga label to an item,

FIG. 2b shows, by way of example, in a three dimensional view, a

FIG. 3a shows, by way of example, in a three dimensional view, a labeledtransparent item,

FIG. 3b shows, by way of example, in a three dimensional view, a labeledmetallic item,

FIG. 3c shows, by way of example, in a three dimensional view, a labeleditem, which has a flat labeled portion,

FIG. 4a shows, by way of example, in a cross-sectional view, refractiveindices of the structural layers,

FIG. 4b shows, by way of example, in a cross-sectional view, reflectionof light from the optical interfaces,

FIG. 5a shows, by way of example, in a cross-sectional view, an unevensurface of an item,

FIG. 5b shows, by way of example, in a cross-sectional view, a labelattached to the uneven surface,

FIG. 6a shows, by way of example, in a cross-sectional view, alabelstock, which comprises a plurality of labels carried by a commonrelease layer,

FIG. 6b shows, by way of example, in a cross-sectional view, theposition of a label with respect to an item before contact,

FIG. 6c shows, by way of example, in a cross-sectional view, theposition of the label when the leading edge of the label contacts theitem,

FIG. 6d shows, by way of example, in a cross-sectional view, theposition of the label after the leading edge of the label

FIG. 6e shows, by way of example, in a cross-sectional view, theposition of the label when the label is pressed by a pressing member,

FIG. 6f shows, by way of example, in a cross-sectional view, theposition of the label after the item has been rotated,

FIG. 6g shows, by way of example, in a cross-sectional view, labeling ofseveral items,

FIG. 6h shows, by way of example, the velocity of the release liner as afunction of time during the labeling process,

FIG. 6i shows, by way of example, method steps for high speed labeling,

FIG. 7a shows, by way of example, in a cross-sectional view, an airbubble trapped between the adhesive layer and the item,

FIG. 7b shows, by way of example, in a cross-sectional view, diffusionor air away from the air bubble,

FIG. 7c shows, by way of example, in a cross-sectional view, a portionwhere the air bubble has been substantially eliminated,

FIG. 8 shows, by way of example, a product chain from a label laminateweb to a labelled product,

FIG. 9a shows, by way of example, in a top view, a printed web,

FIG. 9b shows, by way of example, in a cross-sectional view, a releaseliner laminated to the printed web,

FIG. 9c shows, by way of example, in a cross-sectional view, forming

FIG. 9d shows, by way of example, in a top view, a labelstock comprisinga plurality of labels,

FIG. 9e shows, by way of example, method steps for providing a pluralityof labels,

FIG. 10a shows, by way of example, in a cross-sectional view, a labelcomprising a release coating on the uppermost surface,

FIG. 10b shows, by way of example, in a cross-sectional view, aplurality of stacked linerless labels,

FIG. 10c shows, by way of example, in a top view, a labelstockcomprising a plurality of linerless labels,

FIG. 10d shows, by way of example, in a cross-sectional view, a roll,which comprises a plurality of linerless labels,

FIG. 11a shows, by way of example, steps of a production chain, and

FIG. 11b shows, by way of example, various resources of a supply chain.

All drawings are schematic.

DETAILED DESCRIPTION Adhesive Label

Referring to FIGS. 1a, 1b, and 1c , the adhesive label 100 may comprisea face layer 10, and an adhesive layer 20. The adhesive label 100 mayoptionally comprise a printed region 30. The printed region 30 may belocated between the face layer 10 and the adhesive layer 20 (FIGS. 1aand 1 b). The face layer 10 may mechanically protect the printed region30.

The printed region 30 may be implemented on top of the face layer 10(FIG. 1c ). The printed region 30 may comprise a marking MRK1. Themarking MRK1 may comprise e.g. alphanumerical symbols and/or graphics.

Referring to FIG. 1a , the adhesive layer 20 may comprise one or moreadhesive sub-layers 21, 22. The adhesive layer 20 may consist of one ormore adhesive sub-layers 21, 22. The adhesive layer 20 may adhere to thesurface SRF0 of an item ITE1 (FIG. 2a ). The adhesive layer 20 may forman adhesive bond between the face layer 10 and the surface SRF0 of theitem ITE1. The uppermost sub-layer 21 may be in contact with the facelayer 10, and the lowermost sub-layer 22 may be in contact with theitem. At least a portion of the uppermost sub-layer 21 may be in contactwith the face layer 10. The label 100 may comprise a printed region 30implemented between the face layer 10 and the adhesive layer 20 suchthat at least a portion of the uppermost sub-layer 21 is in contact withthe face layer 10. The lowermost sub-layer 22 may adhere to the surfaceof an item. The chemical composition of the uppermost sub-layer 21 maybe different from the chemical composition of the lowermost sub-layer22. The composition of the sub-layers 21, 22 may be tailored to optimizethe optical and mechanical properties of the label, and/or in order toreduce material costs. For example, the chemical composition of thelowermost sub-layer 22 may be selected to maximize adhesion. Forexample, the chemical composition of the uppermost sub-layer 21 may beselected to minimize optical reflectivity of the interface between theuppermost sub-layer 21 and the face layer 10. For example, the chemicalcomposition of the lowermost sub-layer 22 may be selected to minimizeoptical reflectivity the interface between the lowermost sub-layer 22and the item.

Referring to FIG. 1b , the adhesive layer 20 may consist of only onesub-layer, wherein the uppermost sub-layer may also be act as thelowermost sub-layer.

The label 100 may comprise a substantially clear portion. The clearportion may be called as substantially transparent portion. The facelayer 10 may comprise or consist essentially of suitable clear,semicrystalline polymeric film, in order to provide the clear portion.The face layer 10 may comprise semi-crystalline polymeric film. Thesemi-crystalline polymeric film may be e.g. a polyester film. Thepolyester film may be e.g. polyethylene terephthalate (PET). Thepolyester film may be e.g. polyethylene naphthalate (PEN).

The adhesive layer 20 may comprise transparent polymeric adhesive. Theadhesive layer 20 may comprise acrylic polymeric adhesive. The polymericadhesive may also be e.g. a non-water whitening polymeric adhesive

The thickness d₁₀ of the face layer 10 may be e.g. in the range of 10 μmto 50 μm, and the thickness d₂₀ of the adhesive layer 20 may be e.g. inthe range of 8 μm to 25 μm. The thickness d₂₀ of the adhesive layer 20may be smaller than 95% of the thickness d₁₀ of the face layer 10.

The thickness of d₁₀ of the face layer 10 may be e.g. substantiallyequal to 18 μm. The thickness of d₁₀ of the face layer 10 may be e.g.substantially equal to 19 μm. The thickness of d₁₀ of the face layer 10may be e.g. substantially equal to 23 μm.

The thickness d₂₀ of the adhesive layer may be selected according to thethickness of the face layer. The thickness d₂₀ of the adhesive layer 20may be e.g. in the range of 50% to 95% of the thickness d₁₀ of the facelayer 10.

When the thickness d₁₀ of the face layer 10 is in the range of 12 μm to25 μm, the thickness d₂₀ of the adhesive layer 20 may be e.g. in therange of 8 μm to 24 μm.

The refractive index n₂ of the uppermost adhesive sub-layer 20 may bee.g. in the range of 80% to 98.5% of the refractive index n₁ of thesemi-crystalline polymeric film. The refractive index n₂ of theuppermost adhesive sub-layer 20 may be e.g. in the range of 80% to 98.5%of the refractive index n₁ of the semi-crystalline polymeric film at thewavelength of 550 nm. Consequently, the reflection coefficient R₂ of theoptical interface between the face layer 10 and the adhesive layer 20may be kept below a predetermined value. The refractive index n₁ and n₂may be determined e.g. at the wavelength of 550 nm. The wavelength of550 nm may be considered to represent green light.

The label 100 may be provided such that the label 100 is carried by arelease liner 90 (FIG. 6a ). The adhesive layer 20 may be locatedbetween the face layer 10 and the release liner 90. The release liner 90may comprise e.g. polyester or paper. The release liner 90 may comprisea non-blocking surface layer 91 (FIG. 9b ). The surface layer 91 maycomprise e.g. silicone polymer. The label 100 may be attached to arelease liner 90 comprising a non-blocking surface layer 91, such thatthe adhesive layer 20 is between the face layer 10 and the non-blockingsurface layer 91 of the release liner 90.

The uppermost layer of the label 100 may consist of polyester film, orthe face layer 10 of the label 100 may be optionally coated with arelease coating. The release coating may e.g. facilitate keeping thelabel clean after it has been attached to an item.

The combination of a plurality of labels and the release layer carryingthe labels may be called as a labelstock STO1 (FIG. 6a ). The releaselayer may support a plurality of labels. The labelstock STO1 maycomprise a plurality of labels attached to the release layer 90.

The total thickness d_(tot) of the label 100 may be e.g. in the range of150% to 195% of the thickness d₁₀ of the face layer 10, when the label100 is not attached to the release layer. The total thickness d_(tot) ofthe label 100 may mean the thickness from the uppermost surface of theface layer 10 to the lowermost surface of the lowermost adhesivesub-layer.

The label 100 may also be provided as a linerless label (FIG. 10a ). Aplurality of linerless labels may be supplied as a roll (FIG. 10d ).When the label is supplied as a linerless label, the uppermost surfaceof the label 100 may be coated with a release coating in order to avoidblocking of the roll.

Face Layer

The face layer 10 of the label 100 may provide e.g. one or more of thefollowing functions:

-   -   the face layer 10 may carry one or more printed regions 30,    -   the face layer 10 may protect the one or more printed regions        30,    -   the face layer 10 may provide transparency,    -   the face layer 10 may provide a no-label look    -   the face layer 10 may provide a vanishing edge VE1,    -   the face layer 10 may provide low visual contrast when compared        with an exposed (non-labelled) portion of the labeled item,    -   the face layer 10 may provide a highly reflective upper surface,    -   the face layer 10 may provide a lower surface, which has a low        optical reflectivity,    -   the face layer 10 may provide sufficient stiffness for high        speed dispensing of the label 100,    -   the stiff and thin face layer may facilitate controlling the        dispensing geometry,    -   the face layer may provide longitudinal tension for controlling        dispensing geometry,    -   the face layer may allow diffusion of air away from air bubbles        trapped beneath the label,    -   the face layer 10 may smooth out irregularities of the item by        conforming to the curved shape of an item,    -   the face layer 10 may carry other labels in linerless        applications.

Material of the Face Layer

The face layer 10 may comprise thermoplastic polymer. Preferably, theface layer 10 is semi-crystalline polymer, such as polyester. Polyesterssuch as polyethylene terephthalate and polyethylene naphtalate can be insemicrystalline form. The face layer 10 may be of polyethyleneterephthalate or polyethylene naphtalate. Polyethylene terephthalate ofthe layer 10 may have an a density in the range of 1.35 to 1.45 g/cm³,preferably close to 1.4 g/cm³. The density may be determined accordingto ASTM D-1505.

The optical characteristics of the filmic polyester material may dependon the crystallinity of the polymer, on the alignment of the molecularchains, and on the thickness of the filmic polyester material. Thecrystallinity of the polymer and the alignment of the molecular chainsmay be controlled by the manufacturing method of the polyester material.Polyesters such as polyethylene terephthalate or polyethylene naphtalatemay have a crystal size distribution. Depending on the crystal sizedistribution, the polymer material may be arranged to appeartransparent, opaque or white. The semi-crystalline polymer material maycomprise ordered regions where the polymer chains are both aligned andfolded. Said ordered regions may be called e.g. as crystallites,crystals or grains. The crystallites may act as scattering centers forlight. The characteristic size of the crystallites may be e.g. smallerthan 400 nm, in order to provide a substantially transparent material.

Optical Absorption

The face layer 10 may be relatively thin. The thickness d₁₀ of the facelayer may be e.g. smaller than or equal to 25 μm, smaller than or equalto 20 μm, or even smaller than or equal to 15 μm. The thickness d₁₀ ofthe face layer may be e.g. in the range of 10 μm to 25 μm. The thinlayers 10, 20 may reduce the length of the optical path of light whensaid light travels through the label 100. The short length of theoptical path may reduce the attenuation of the light travelling throughthe label 100. Consequently, the label 100 may appear to be clear evenin a situation where the face layer 10 and/or the adhesive layer 20would contain slightly light-absorbing material. The label 100 mayappear to be clear even in a situation where the face layer 10 and/orthe adhesive layer 20 contain impurities. This may reduce materialcosts.

Optical Scattering by the Face Layer (Haze Level)

Optical scattering by the face layer 10 may be determined from a labelor a label layer as a haze value e.g. according to standard ASTM D-1003.The face layer 10 may have a low haze level. The face layer may befilmic polyester having a haze value equal to or less than 6.5%,advantageously equal to or less than 4.0%, and preferably equal to orless than 3.6%. The haze value of the face layer 10 may be e.g. in therange of 1.0% to 3.6%. The face layer 10 may also comprise “ultra” clearpolyester film, wherein the haze value of the face layer 10 may be inthe range of 0.5% to 1.0%. The face layer 10 may be filmic polyesterhaving a thickness in the range of 12 μm to 23 μm (0.48 mil to 0.92 mil)wherein the haze value of the face layer 10 may be in the range of 0.5%to 3.6%.

Stiffness

The stiffness of the label 100 may be mainly determined by the stiffnessof the face layer 10. The stiffness of the face layer 10 may be equal tothe second moment of area multiplied by the tensile modulus. Therelative stiffness of the face layer 10 may be equal to the stiffness ofthe face layer 10 divided by the thickness d₁₀ of the face layer 10. Theface layer 10 may be uniaxially or biaxially oriented to provide asufficient stiffness for the label 100 such that the label 100 may bedispensed at high-speed on a moving item ITE1.

The face layer 10 has a first tensile modulus in the machine direction(MD) and a second tensile modulus (CD) in the cross direction. The facelayer may be filmic polyester having a tensile modulus, which is e.g.higher than 2700 MPa. The face layer may be filmic polyester having atensile modulus, which is higher than 4000 MPa. The face layer may befilmic polyester having a tensile modulus, which is higher than 4150MPa.

When the polyester film is bi-axially oriented, the tensile modulus ofthe polyester film may be substantially similar in both machinedirection and cross direction. The face layer 10 may be made of a PETfilm, wherein the tensile modulus of the PET film may be e.g. thanhigher than 4000 MPa in the machine direction (MD), and/or the tensilemodulus of the PET film may be higher than 4000 MPa in the crossdirection (CD). The face layer 10 may be made of a PET film, wherein thetensile modulus of the PET film may be e.g. than higher than or equal to4150 MPa in the machine direction (MD), and/or the tensile modulus ofthe PET film may be higher than or equal to 4150 MPa in the crossdirection (CD). The tensile modulus may be determined according tostandard ASTM D 882.

The stiffness of the label may be selected to be in a predeterminedrange so that the thin face layer may still be able to conform to theshape of the item. When attached to the item, the face material may bendand conforms to a principal radius of curvature of the substratesurface.

Hardness of the Face Layer

The hardness of the face layer 10 may be increased e.g. by uniaxial orbiaxial stretching so as to reduce ghosting of the label when the labelis supplied as a part of a wound roll. The term “ghosting” may mean avisible deformation made by the edge of a second label on the surface ofa first label when the edge of said second label is pressed against thesurface of the first label. The hardness of the face layer 10 may bee.g. higher than 94 in the Rockwell M scale.

Adhesive Layer

The adhesive layer 20 of the label 100 may have e.g. one or more of thefollowing functions:

-   -   the adhesive layer 20 may adhere to the surface of an item,    -   the adhesive layer 20 may provide transparency,    -   the adhesive layer 20 may reduce the reflection coefficient of        the interface between the face layer 10 and the adhesive layer        20,    -   the adhesive layer 20 may fill and hide optical defects of the        surface of the item,    -   the adhesive layer 20 may allow separation of the label from a        release liner,    -   the adhesive layer 20 may at least partly control longitudinal        tension of the label during dispensing,    -   the adhesive layer 20 may reduce the size of gas bubbles by        wetting,

The label 100 comprises an adhesive layer 20 of polymeric material. Theadhesive layer 20 may be arranged to attach the label on a substratesurface SRF0. Composition of the adhesive layer in this context refersto an adhesive substance, such as a polymeric compound, which has atendency to adhere to the surface of an item by means of chemicaladhesion and/or by means of dispersive adhesion. The adhesive substanceof the layer 20 may adhere to the surface of an item by means ofcovalent bonds and/or by intermolecular attraction.

The adhesive layer composition may further be arranged to promote theoptical characteristics of the label, such as clarity and “no-labellook”.

The adhesive layer may be configured to be self-adhesive, such that thelabel may be attached on the intended substrate surface material bypressing. The adhesive layer may comprise pressure sensitive adhesive(PSA). The adhesive layer may comprise pressure sensitive acrylicpolymer adhesive.

The adhesive layer may comprise or consist essentially of polymericadhesive. The adhesive layer may comprise or consist essentially of apolymeric adhesive suitable for clear label applications.

The polymeric adhesive of the layer 20 may be substantially transparentso that the adhesive layer of the label may contribute to the “no-labellook”. The refractive index of the polymeric adhesive may be selected toreduce reflectivity of the interface between the adhesive layer 20 andthe face layer 10. The refractive index of the polymeric adhesive may beselected to reduce reflectivity of the interface between the adhesivelayer 20 and the item ITE1.

Tack Value

The adhesive may be a pressure sensitive adhesive. The adhesive of thelayer 20 may have a sufficient tack value so that the label is notpeeled away from a labeled item during normal use of the labeled item.The adhesive of the layer 20 may have a sufficient tack value so thatthe label may withstand temperature fluctuations and humidity.

The tack value of the polymeric adhesive may be e.g. higher than orequal to 9N, such that the label may be firmly attached to the surfaceof the item.

The polymeric adhesive of the label may be arranged to have a releasevalue higher than 15 g, preferably equal to or higher than 19 g, such asin the range of 19 to 23 g, as measured in a TLI release testeraccording to a modified FINAT test method, wherein a test tape is pulledat an angle of 180 degrees at a velocity of 1200 inches per minute,wherein the width of the test tape is equal to 2 inch, and the adhesivelayer of the test tape consists of said polymeric adhesive.

The loop tack value of the polymeric adhesive may be equal to or higherthan 0.4 kN/m. The loop tack value may be measured according to themethod “LIB” as specified by the TLMI standardizing organization. TLMImeans the Tag and Labels Manufacturing Institute, USA.

Wetting

The adhesive layer have an ability of eliminate small irregularitiessuch as scratches from the substrate surface. A well-wetting adhesivemay have an ability to spontaneously spread on a surface when theadhesive has been brought into contact with said surface. Wettabilitymay define the capability of the polymeric adhesive to spread on a solidsurface upon contact to the surface. The wetting properties of thepolymeric adhesive may be selected such that when applied on a substratesurface having surface roughness, the polymeric adhesive may flow to thelower parts or valleys of the substrate surface. The adhesive materialof the label may fill the lower parts or valleys of an irregular surfaceof the item.

The wetting properties of the polymeric adhesive applied on the surfaceof a material may be described by a contact angle (θ_(c)) of thepolymeric adhesive. The contact angle (θ_(c)) may depend on thecomposition of the polymeric adhesive and on the composition of thematerial. When applied on a solid substrate surface, the polymericadhesive has a tendency to spread until the internal forces of theadhesive, the gravity forces and the surface tension forces are inbalance, such that an equilibrium state is reached. The advancingcontact angle (θ_(c)) for wetting a polyethylene terephthalate surfacewith the polymeric adhesive may be e.g. lower than 70° when determinedat the temperature of 25° C. In case of spontaneous wetting, theadvancing contact angle (θ_(c)) for wetting a polyethylene terephthalatesurface with the polymeric adhesive may be e.g. lower than 70° whendetermined at the temperature of 25° C. The contact angle may bedifferent when the adhesive layer 20 is compressed between the facelayer 10 and the surface SRF0 of the item ITE1.

The adhesive layer may have a low surface energy level, so as to improvethe wettability of the surface SRF0 of the item ITE1. The surfacetension of the polymeric adhesive may be e.g. lower than or equal to 40dyn/cm when determined at the temperature of 25° C. The adhesive havinga surface tension lower than or equal to 40 dyn/cm may be suitable forforming an adhesive bond with e.g. polyethylene terephthalate, glass,and/or aluminium.

Bleeding

When the labelstock is wound to form a roll, the pressure of the rollmay cause the adhesive to bleed at the edges of the label. Whendispensing the labels, the bleeding may cause accumulation of adhesiveat different parts of the dispensing unit. The accumulation of adhesivemay disturb operation of the labeling apparatus.

The low thickness of the adhesive layer 20 may reduce the risk ofbleeding. The adhesive layer 20 may have a low coat weight. The coatweight of the adhesive may be e.g. in the range of 5 to 15 g/m².

Release Liner

The adhesive label 100 may be carried on a release liner 90. The releaseliner 90 comprising a release layer 91 may provide a platform for highspeed dispensing of the label 100. For example, the release layer 91 maycomprise or consists essentially of a silicone polymer. The releaselayer 91 may have low friction, low dusting and/or anti-adhesiveproperties such that the adhesive label 100 may be detached from theliner 90.

The release liner 90 may comprise e.g. polyester or paper. The releaseliner 90 may be made of clear polyester film having properties equal tothe face layer described above. Advantageously, the release liner 90 maycomprise or consist essentially of polyester, such as polyethyleneterephthalate. The mechanical properties of the release liner 90 may besubstantially similar to the mechanical properties of the face layer.

The coat weight of the release layer 91 applied on the release layer 90may be e.g. equal to or smaller than 0.2 g/m². The coat weight of therelease layer 91 applied on the release layer 90 may be e.g.substantially equal to 0.1 g/m².

Release Properties

A plurality of labels may be carried on a release liner 90. A firstlabel 100, 100 a may be separated from the release liner 90 before thefirst label 100, 100 a is attached to an item IE1, ITE1 a. The adhesiveof the layer 20 and the release liner 90 may be selected such that theforce needed to separate the label from the liner is higher than athreshold limit. The force may be used e.g. to control the longitudinaltension of the label during the dispensing. The force may be used e.g.to control the dispensing geometry. The release value of the label maybe e.g. higher than 0.15 N (15 g) in a situation where a sample piece ofthe label is separated from the release liner 90 at an angle of 180° ata velocity of 1200 inches per minute at a temperature of 25° C., whereinthe width of said sample piece is equal to 2 inches.

The 180° Peel Adhesion value of the polymeric adhesive may be equal toor higher than 3.2 pounds/inch, when measured after a 15 minutes dwelltime. Advantageously, the 180° Peel Adhesion value of the polymericadhesive may be equal to or higher than 4.0 pounds/inch, when measuredafter a 24 hour dwell time. The 180° Peel Adhesion may be measured bypeeling a test tape from AISI 304 stainless steel surface according tothe standard PSTC-1 for Peel Adhesion by the Pressure Sensitive TapeCouncil. The test tape may comprise a dry film of adhesive cast directlyonto a polyester film, wherein the thickness of the adhesive film may be25 μm and the thickness of the polyester film may be 50 μm.

A plurality of labels may also be provided as linerless labels, i.e.without a liner. The linerless labels may be wound to form a roll RLL1(FIG. 10d ). The labels 100 a, 100 b may form a linerless labelstockSTO1. The labelstock STO1 may be provided as a wound roll RLL1. A firstlabel 100, 100 a of the roll RLL1 may be separated from second label ofsaid roll RLL1 before the first first label 100, 100 a is attached to anitem IE1, ITE1 a. When the linerless labelstock STO1 is unwound from theroll RLL1, the adhesive layer 20 may be configured to separate from thewound roll RLL1 without damaging the other labels of the roll RLL1. Toprevent the adhesive layer 20 from damaging other labels on the rollRLL1, the uppermost surface SRF1 of the label 100 may comprise a releasecoating 91, e.g. silicone polymer applied on top of the face layer 10.

Labeled Products

Referring to FIGS. 2a and 2b , the label 100 may be attached to an itemITE1 to form a labeled item PROD1. The reflective properties of thelabel 100 may substantially match with the reflective properties of theitem ITE1. Thus, the edge VE1 of the label 100 may be less easy detectvisually. In this sense, the label attached to the item may have a“vanishing edge” VE1. The label 100 of the labeled item PROD1 may have a“vanishing edge” VE1.

Referring to FIG. 3a , the item ITE1 may comprise e.g. transparent glassor plastic. The item ITE1 may be e.g. a container for a beverage. Theitem ITE1 may be e.g. a glass bottle or a plastic bottle. The item ITE1may be e.g. a transparent container made of glass. The item ITE1 may bee.g. a transparent container made of PET. The refractive index of theadhesive layer may substantially match with the refractive index ofitems made of glass or PET.

The label 100 may be used e.g. for labeling a bottle, which containbeverage. The label 100 may be used e.g. for labeling bottles, whichcontain beverage.

In particular, the label 100 may be used for labeling recycled glasscontainers, e.g. glass bottles. A recycled glass bottle may have ascratched surface SRF0, and the label 100 may improve the visualappearance of the scratched surface SRF0.

The label 100 may be used e.g. for labeling a container, which contain ahousehold chemical.

Referring to FIG. 3b , the label 100 may also be attached e.g. to alacquered metallic surface. The label 100 may be attached e.g. to alacquered aluminum can. The label 100 may hide scratches orirregularities of the metallic surface. The high gloss of the label 100may even further improve the visual appearance of the reflective surfaceof the metallic surface.

Referring to FIG. 3c , the label 100 may be applied on a substantiallyplanar surface.

Optical Properties

The label 100 may comprise a clear portion. The label 100 may comprise aclear portion to transmit illuminating light LB1 through the uppermostsurface SRF1 to the interface SRF3 between the adhesive layer 20 and theitem ITE1.

The face layer 10 of the label 100 may comprise a clear portion. Theclear portion of the face layer 10 may transmit illuminating light LB1through the uppermost surface SRF1 to a printed region 30 between theface layer 10 and the adhesive layer 20, and to transmit reflected lightback from the printed region 30 through the uppermost surface SRF1 to aviewer.

“No Label—Look”

The reflective properties of the label may substantially match with thereflective properties of the item. Thus, the edge VE1 of the label 100may be less easy detect visually, see e.g. FIGS. 2a and 2b . In thissense, the label attached to the item may have a “vanishing edge” VE1.

The relative difference between the reflection coefficient of theuppermost surface of the label and the reflection coefficient of theexposed surface of the item may be e.g. smaller than 20%. The surfaceSRF0 of the item ITE1 may have a first reflection coefficient R_(c), alabeled portion of the labeled item PROD1 may have a second reflectioncoefficient R_(tot), and the relative difference ((R_(c)−R_(tot))/R_(c))between the first reflection coefficient and the second reflectioncoefficient may be e.g. smaller than 20%. Consequently, the visualcontrast at the edge of the label may be less easy to detect. The edgeVE1 of the label may be less easy to detect visually.

Thanks to the thin adhesive layer, the printed region 30 and/or markingMRK1 may be close to the surface of the item. Consequently, the printedregion 30 may look visually similar to a (comparative) region whichwould have been printed on the surface of the item. The printed region30 may look visually indistinguishable from a region printed on thesurface of a similar reference item.

The reflection coefficient of the interface between the adhesive layerand the face layer may be low. The uppermost surface of the label mayreflect light more efficiently than the lower surfaces of the label, soas to provide a visually sharp reflection. The interface SRF2 betweenthe face layer 10 and the adhesive layer 20 may have a reflectioncoefficient R₂, the uppermost layer SRF1 of the label 100 may have areflection coefficient R₁, and the reflection coefficient R₂ of theinterface SRF2 may be smaller than e.g. 10% of the reflectioncoefficient R₁ of the uppermost layer SRF1. The refractive index n₂ ofthe polymeric adhesive of the layer 20 may be close to the refractiveindex n₁ of the face layer. The refractive index n₂ of the polymericadhesive may be e.g. in the range of 80% to 98.5% of the refractiveindex n₁ of the polyester film at the wavelength of 550 nm.

In particular, the refractive index n₂ of the polymeric adhesive may bein the range of 90% to 98.5% of the refractive index n₁ of the polyesterfilm at the wavelength of 550 nm.

High Gloss

The label may provide a high gloss surface, which may substantiallymatch e.g. with the high gloss of a glass or aluminum surface. Thelabeled portion of a labeled item may even have a higher gloss and/orsmoother upper surface than the bare surface of the item. The label maysubstantially improve the surface quality of the item.

The reflection coefficient and the gloss of the uppermost surface of thelabel may depend on the difference between the refractive index of theface layer and the refractive index of air. The refractive index of theface layer may be increased by stretching the face layer, in order toprovide a higher gloss. The face layer may be bi-axially stretched. Therefractive index n₁ of the stretched polyester film may be e.g. in therange of 1.55 to 1.65 at the wavelength of 550 nm. In particular, theface layer 10 may have been uniaxially or biaxially stretched so thatthe refractive index of the face layer is higher than 1.60. The labelmay be provided such that the uppermost surface is an interface betweenpolyethylene terephthalate (PET) and air. The uppermost surface of thelabel may be implemented such that it does not comprise siliconepolymer.

Reflection Coefficients

Referring to FIGS. 4a and 4b , the reflective properties of the labeleditem may depend on the refractive indices of the layers of the label. n₀denotes the refractive index of air AIR1. n₁ denotes the refractiveindex of the face layer 10. n₂ denotes the refractive index of theadhesive layer 20. n_(c) denotes the refractive index of the materialMAT1 of the surface of the item ITE1.

The label 100 may comprise a clear portion to transmit illuminatinglight LB0 to the surface of the item ITE1 and to transmit reflectedlight LB3 from the surface of the item ITE1 to the eye of a viewer.

SRF0 may denote the interface between air AIR1 and the bare surface ofthe item ITE1. SRF1 may denote the interface between air AIR1 and theface layer 10. SRF2 may denote the interface between the face layer 10and the adhesive layer 20. SRF3 may denote the interface between theadhesive layer 20 and the surface of the item ITE1. The reflectioncoefficient R of the interface SRF0 may depend on the refractive indicesn₀ and n_(c) according to the following equations:

$\begin{matrix}{R_{s} = {\frac{{n_{0}\mspace{11mu} \cos \mspace{11mu} \theta_{i}} - {n_{c}\mspace{11mu} \cos \mspace{11mu} \theta_{t}}}{{n_{0}\mspace{11mu} \cos \mspace{11mu} \theta_{i}} + {n_{c}\mspace{11mu} \cos \mspace{11mu} \theta_{t}}}}^{2}} & \left( {1a} \right) \\{R_{p} = {\frac{{n_{0}\mspace{11mu} \cos \mspace{11mu} \theta_{t}} - {n_{c}\mspace{11mu} \cos \mspace{11mu} \theta_{i}}}{{n_{0}\mspace{11mu} \cos \mspace{11mu} \theta_{t}} + {n_{c}\mspace{11mu} \cos \mspace{11mu} \theta_{i}}}}^{2}} & \left( {1b} \right) \\{R = \frac{R_{s} + R_{p}}{2}} & \left( {1c} \right)\end{matrix}$

R_(s) denotes reflection coefficient for s-polarized light, R_(p)denotes reflection coefficient for p-polarized light, R denotes theaverage of the coefficients R_(s) and R_(p), θ_(i) denotes input angleof illuminating light, and θ_(t) output angle of refracted light. Thedirection of illuminating light may be e.g. perpendicular to the surfaceSRF0, and the angles θ_(i) and θ_(t) may be equal to zero. When theinput angle θ_(i) is equal to zero, the reflection coefficient R_(c) ofthe interface SRF0 may be calculated according to the followingequation:

$\begin{matrix}{R_{c} = \frac{\left( {n_{0} - n_{c}} \right)^{2}}{\left( {n_{0} + n_{c}} \right)^{2}}} & \left( {1d} \right)\end{matrix}$

When the input angle θ_(i) is equal to zero, the reflection coefficientR₁ of the interface SRF1 may be calculated according to the followingequation:

$\begin{matrix}{R_{1} = \frac{\left( {n_{0} - n_{1}} \right)^{2}}{\left( {n_{0} + n_{1}} \right)^{2}}} & (2)\end{matrix}$

When the input angle θ_(i) is equal to zero, the reflection coefficientR₂ of the interface SRF2 may be calculated according to the followingequation:

$\begin{matrix}{R_{1} = \frac{\left( {n_{1} - n_{2}} \right)^{2}}{\left( {n_{1} + n_{2}} \right)^{2}}} & (3)\end{matrix}$

When the input angle θ_(i) is equal to zero, the reflection coefficientR₂ of the interface SRF2 may be calculated according to the followingequation:

$\begin{matrix}{R_{2} = \frac{\left( {n_{2} - n_{c}} \right)^{2}}{\left( {n_{2} + n_{c}} \right)^{2}}} & (4)\end{matrix}$

The surface of the item and the label 100 may be illuminated withilluminating light LB0. The interface SRF0 may provide a reflected beamLBC by reflecting light of the illuminating beam LB0. The interface SRF1may provide a reflected beam LB1 by reflecting light of the illuminatingbeam LB0. The interface SRF2 may provide a reflected beam LB2 byreflecting light of the illuminating beam LB0. The interface SRF3 mayprovide a reflected beam LB3 by reflecting light of the illuminatingbeam LB0. The printed region 30 may provide a reflected beam LB30 byreflecting light of the illuminating beam LB0. The printed region 30′may provide a reflected beam LB30′ by reflecting light of theilluminating beam LB0. A human observer viewing a clear labeled portiondetects the combined intensity of the beams LB1, LB2, LB3. R_(c) denotesthe reflection coefficient of the bare surface SRF0 of the item ITE1.The total reflection coefficient R_(tot) of a clear labeled portion maybe equal to the sum of the reflection coefficients of the surfaces SRF1,SRF2, and SRF3.

R _(tot) =R ₁ +R ₂ +R ₃  (5).

To the first approximation, the total reflection coefficient R_(tot) ofa clear labeled portion may be substantially equal to the sum of thereflection coefficients of the surfaces SRF1, SRF2, and SRF3.

To the first approximation, the visual contrast between the clearlabeled portion and the bare surface of the item may be proportional tothe relative difference (R_(c)−R_(tot))/R_(c).

Smoothing Effect

The label 100 may be arranged to make certain imperfections of the itemITE1 less visible. For example, the label may provide a high qualityappearance by smoothing an irregular shape of the item, and/or by hidingscratches of the surface of the item ITE1. The adhesive layer 20 mayhide scratches of the surface of the item ITE1, and the thin face layer10 may conform to the shape of the item. The face layer 10 may conformto the shape of the item such that the thin layer of adhesive layer 20may be sufficient to hide visually detectable scratches of the surfaceof the item ITE1.

In case of a transparent item, the reflection coefficient R₃ of theinterface between the adhesive layer 20 and the surface of the item maybe low.

Referring to FIGS. 5a, and 5b , the item ITE1 may have one or morecurved portions REG1, one or more irregular portions REG2, and/or one ormore curved irregular portions REG3. The irregular portions REG2, REG3may also be called e.g. a rough portions. The curved portion REG1 mayhave a radius of curvature r₁. The radius of curvature r₁ of the itemITE1 may be e.g. smaller than 50 mm.

The surface roughness of the portions may be specified e.g. by providinga R_(a)-value, which indicates the arithmetic average of the absolutevalues of the profile height deviations from the mean line, recordedwithin an evaluation length L2. In case of the thin face layer 10, therelevant evaluation length L2 may be e.g. equal to 1.0 mm. h2 may denotea maximum depth of a valley between two peaks within the evaluationlength L2. d₂(x) may denote a distance between the face layer 10 and thesurface of the item ITE1 at a position x. The average value of thedistance d₂ may be substantially equal to the thickness of the adhesivelayer 20.

The thickness d₁₀ of the label 100 may be e.g. in the range of 10 μm to25 μm. Thanks to the small thickness, the label 100 may conform to thecurved shape of the item.

An average radius (r₁′) of curvature of the label (100) at a portion(REG1) may be e.g. in the range of 1.001 (=(10 mm+10 μm)/10 mm) to 1.005(=(5 mm+25 μm)/5 mm) times the average radius (r1) of curvature of saidportion (REG1), in a situation where the average radius (r1) ofcurvature of the label (100) at said portion (REG1) is in the range of 5mm to 10 mm, and the width of said portion (REG1) is equal to 5 mm.

Conforming to the shape of the item may ensure that the label may befirmly attached to the item even when the thickness of the adhesivelayer is small. Consequently, optical reflections from the lower surfaceof the adhesive layer do not disturb the visual appearance of the labelattached to the item. For example, more than 95% of the area of thelabel may be in contact with the surface of the item.

For example, an average thickness of an air gap enclosed between theadhesive layer 20 and the item ITE1 may be lower than 0.1 μm in an area,which overlaps 95% of the area of the label 100. 0.1 μm corresponds toan air gap, which is less than ¼ of the wavelength λ=550 nm. An air gapgreater than 0.1 μm may cause a disturbing reflection from the interfacebetween the air and the adhesive. An air gap greater than 0.1 μm maycause a disturbing reflection from the interface between the air and thesurface of the item. An air gap greater than 0.1 μm may cause adisturbing reflection from an irregular surface of the item.

The label may smooth out irregularities and/or unevenness of the surfaceof the item. The adhesive may fill scratches on the surface of the item.The combination of the thin face layer and the adhesive may provide acapability to fill irregularities of a curved surface. The surfaceroughness value Ra of the surface of the item ITE1 may be e.g. in therange of 0.5 μm to 5.0 μm. For example, average thickness of airenclosed between the adhesive layer 20 and the item ITE1 may be lowerthan 0.1 μm in an area, which overlaps 95% of the area of the label 100,when the surface roughness value Ra of the item ITE1 is in the range of0.5 μm to 5.0 μm.

Method for Labeling Items

Referring to FIG. 6a , a labelstock STO1 may comprise a plurality oflabels 100 carried by a release liner 90. The labels 100 a, 100 b, 100 cmay be e.g. substantially identical.

The labels and the release liner 90 may be optionally wound to form aroll. The labels and the release liner may together form a labelstockSTO1. The labelstock STO1 may be provided as a wound roll. Thelabelstock STO1 may be stored and/or transported as a roll. Thelabelstock STO1 may be unwound from the roll, and the labelstock STO1may be fed to a labeling apparatus 500.

Labeling Apparatus

Referring to FIG. 6b , a labeling apparatus 500 may comprise a peelplate 510, a feeding unit FUNIT1, a pulling unit PUNIT1, and anactuating unit AUNIT1 a. The actuating unit AUNIT1 a may move an itemITE1 a with respect to the peel plate 510. The actuating unit AUNIT1 amay move the item ITE1 a with respect to a frame FRAME0. The actuatingunit AUNIT1 a may cause a translational and/or rotational movement ofthe item ITE1 a with respect to the peel plate 510. The actuating unitAUNIT1 a may cause a translational and/or rotational movement of theitem ITE1 a with respect to the pressure members 530 a, 530 b. Theactuating unit AUNIT1 a may cause a translational and/or rotationalmovement of the item ITE1 a with respect to the frame FRAME0.

The feeding unit FUNIT1 may feed the labelstock STO1 at a velocity v₁ tothe peel plate 510, and the pulling unit PUNIT1 may pull the releaseliner 90 at the velocity v′₁ from the peel plate 510. The feeding unitFUNIT1 and the pulling unit PUNIT1 may be arranged to cause suitabletension in the release liner 90. The velocity v′₁ may be equal to orslightly higher than the velocity v₁. The labelstock STO1 may comprisethe release liner 90, and a plurality of labels 100 a, 100 b. Theapparatus 500 may comprise one or more pressing members 530 a, 530 b topress the label 100 a against the surface of the item ITE1 a after thelabel 100 a has been brought into contact with the item ITE1 a. Thefeeding unit FUNIT1 may comprise e.g. a pair of rollers 521, 522, andthe pulling unit PUNIT1 may comprise e.g. a pair of rollers 523, 524.

The release liner 90 may be bent sharply at the peel plate 510 so as toseparate the label 100 a from the release liner 90. The radius ofcurvature of the release liner 90 at the edge of the peel plate 510 maybe smaller than a predetermined value. The leading edge FE1 of the label100 a may be separated from the release liner 90 by using the peel plate510 so that the adhesive layer of the label 100 a becomes partly exposedin the vicinity of the leading edge FE1. The leading edge FE1 of thelabel 100 a may be moved in the direction SU at a velocity v₁. The label100 a has also a trailing edge TE2. The direction SU may be defined bythe upper surface of the peel plate 510. The direction SU may denote thedirection of movement of the release liner 90 at the upper side of thepeel plate 510. An actuating unit AUNIT1 a may move the surface SRF0 ofthe item ITE1 a in the direction SX at a velocity v_(c). The actuatingunit AUNIT1 a may be e.g. a conveyor belt or a carousel. α₀ denotes anangle between the directions SX and SU. The angle α₀ may be called e.g.as the feeding angle or as the angle of attack. The feeding angle α₀ maybe e.g. in the range of 10° to 30°, preferably in the range of 15° to25°. The amount of air entrained between the label 100 a and the itemITE1 a may be controlled by selecting the feeding angle α₀. Increasingthe feeding angle α₀ may reduce the amount of air trapped between thelabel 100 a and the item ITE1 a.

During high speed labeling, the velocity v_(c) may be e.g. higher than0.5 m/s. The velocity v_(c) may be e.g. in the range of 1 m/s to 10 m/s.The (maximum) velocity v₁ may be substantially equal to the velocityv_(c). The (maximum) velocity v₁ may be e.g. in the range of 90% to 110%of the velocity v_(c). The velocity v₁ may be rapidly accelerated beforebringing the label 100 a into contact with the item ITE1 a.

The item ITE1 a may be at a position x⁻¹ at a time t_(a,−1), before thelabel 100 a contacts the item ITE1 a.

Separating Labels from Release Liner

The release liner 90 may be bent sharply at the peel plate 510 so as toseparate the label 100 a from the release liner 90. The radius ofcurvature of the release liner 90 at the peel plate may be smaller thana predetermined value. The stiffness of the face layer 10 may facilitateseparation of the label from the release liner, in particular when theface layer consists of stretched PET.

Stretching of the Release Liner

The labelstock STO1 may have a velocity v₀ immediately before theentering the feeding unit FUNIT1. The pulling unit PUNIT1 may bearranged to pull the release liner 90 such that the velocity v₁ is e.g.0.5% to 3% higher than the initial velocity v₀. In particular, therelative difference (v₁−v₀)/v₀ may be in the range of 1% to 2%.Consequently, the release liner 90 may be stretched by the pulling unitPUNIT1 such that the relative elongation of the release liner 90 is e.g.in the range of 1% to 2%. The high dimensional stability of PET film ofthe label 100 may cause slipping of the edge of the label 100 a withrespect to the release liner 90 when the release liner 90 is stretched.Thus, the dimensional stability of the label 100 and the stretching ofthe release liner 90 may together facilitate separation of the label 100a from the release liner 90.

Bringing the Label into Contact with the Item

Referring to FIG. 6c , the label 100 a may be moved at a velocity v₁ inthe direction SU, and the item ITE1 a may be simultaneously moved in thedirection SX at the velocity v_(c) such that the leading edge FE1 of thelabel 100 a may contact the surface SRF0 of the item ITE1 a. The leadingedge FE1 of the label 100 a may first contact the surface SRF0 at a timet_(a,0). CL0 denotes a contact line where the label 100 a meets thesurface SRF0 of the item ITE1 a. SL0 denotes a separation line where thelabel 100 a is separated from the release liner 90. The item ITE1 a mayhave a substantially circular perimeter, and the item ITE1 may have anaxis of symmetry AX1. The item ITE1 a may have a (main) radius orcurvature R1. The item ITE1 a may have a diameter, which issubstantially equal to two times the main radius R1.

The separation line SL0 and the contact line CL0 may define a referenceplane REF0. TNG0 denotes the tangent plane of the surface SRF0 at thecontact line CL0. β₀ denotes the angle between the reference plane REF0and the tangent plane TNG0 at the time t_(a,0) when the label 100 afirst contacts the surface SRF0 of the item ITE1 a. The orientation ofthe tangent plane TNG0 with respect to the direction SX may depend onthe relative position of the item ITE1 with respect to the leading edgeFE1. The orientation of the tangent plane TNG0 at the time t_(a,0) maydepend on the timing of the movement of the label 100 a. The angle β₀may be called e.g. as the relative angle or as the impact angle. Theimpact angle β₀ may depend e.g. on the feeding angle α₀, on the positionof the item ITE1 a at the time t_(a,0), and on the position of theleading edge FE1 at the time t_(a,0). The impact angle β₀ may be e.g. inthe range of 10° to 30°, preferably in the range of 15° to 25°.Increasing the impact angle β₀ may reduce the amount of air trappedbetween the label 100 a and the item ITE1 a. The feeding angle α₀ may beselected and the movement of the label 100 a may be timed with themovement of the item ITE1 a such that the impact angle β₀ at the timet_(a,0) is in the range of 10° to 30°, preferably in the range of 15° to25°.

The direction SU may also denote the direction of movement of theleading edge FE1 of the label at the time t_(a,0) of first contact. Thedirection SX may also denote the direction of movement of the surfaceSRF0 of the item ITE1 a at the point where the leading edge FE1 firstcontacts the item ITE1 a.

The method for labeling items ITE1, IT1 a may comprise:

-   -   separating a label 100 a from a release liner 90 by using peel        plate 510,    -   moving the surface SRF0 of an item ITE1 a in a first direction        SX,    -   moving the label 100 a in a second direction SU, and    -   bringing a leading edge FE1 of the label 100 a into contact with        a surface SRF0 of the item ITE1 such that the angle α₀ between        the first direction SX and the second direction SU is in the        range of 10° to 30°.

The label 100 a may comprise:

-   -   a face layer 10, and    -   an adhesive layer 20,

wherein the face layer 10 may comprise semi-crystalline polymeric film,the adhesive layer may consist of one or more adhesive sub-layers, alowermost adhesive sub-layer 20 of said adhesive sub-layers may comprisetransparent polymeric adhesive, the thickness d₁₀ of the face layer 10may be in the range of 10 μm to 50 μm, the thickness d₂₀ of the adhesivelayer 20 may be in the range of 8 μm to 25 μm, and the thickness d₂₀ ofthe adhesive layer 20 may be smaller than 95% of thickness d₁₀ of theface layer 10.

The item ITE1 a may be at a position x₀ at a time t_(a,0), when thelabel 100 a first contacts the item ITE1 a.

Referring to FIG. 6d , the contact line CL0 may have moved farther awayfrom the leading edge FE1 after the time t_(a,0). A portion of the label100 a between the contact line CL0 and the leading edge FE1 may beadhered to the surface SRF0. Substantially the whole portion of thelabel 100 a between the contact line CL0 and the leading edge FE1 may bein contact with the item ITE1 a.

The trailing end TE2 of the label 100 a may still be attached to therelease layer 90. A portion of the label 100 a between the trailing edgeTE2 and the separation line SL0 may still be in contact with the releaseliner 90. The apparatus 500 may be arranged to cause a tension forceTF0, which may control the orientation of the label 100 a. The tensionforce TF0 may keep a portion of the label 100 a substantially straightbetween the contact line CL0 and the separation line SL0. The tensionforce TF0 may keep the impact angle β₀ above a predetermined value, inorder to reduce the amount of air trapped between the label 100 a andthe item ITE1 a. The tension force TF0 may also depend on the peel forceneeded to separate the label 100 a from the release liner 90.

The item ITE1 a may be at a position x₁ at a time t_(a,1), after theleading edge FE1 of the label 100 a has been brought into contact withthe item ITE1 a.

Referring to FIG. 6e , the apparatus 500 may comprise one or morepressing members 530 a, 530 b for pressing the label 100 a against theitem ITE1 a. The pressing member 530 a, 530 b may comprise e.g. elasticmaterial for providing a pressing force. The elastic material may bee.g. porous elastic material. The elastic material may be e.g. foamrubber. The pressing member 530 a may be e.g. a sponge. The pressingmember 530 a, 530 b may be e.g. a roll coated with porous elasticmaterial. The pressing member 530 a, 530 b may be e.g. a brush.

A first pressing member 530 a may be arranged to press the label 100 aagainst the item ITE1 a such that the label 100 a has a radius ofcurvature r₀ at the contact line CL0. The radius r₀ may be e.g. smallerthan 20 mm, preferably smaller than 10 mm. The labeling method maycomprise pressing the label ITE1 a by a pressing member 530 a such thata portion of the label 100 a is temporarily bent, wherein the radius r₀of curvature of the bent portion of the label 100 a is smaller than 10mm.

The first pressing member 530 a may meet the upper side of the label 100a at an auxiliary contact line CL2. When the first pressing member 530 apresses the label 100 a, the trailing edge TE2 of the label 100 a maystill be attached to the release liner 90 such that the apparatus 500may cause the tension force TF0 for keeping a portion of the label 100 asubstantially straight between the separation line SL0 and the auxiliarycontact line CL2. The separation line SL0 and the auxiliary contact lineCL2 may define an auxiliary reference plane REF2. The reference planeREF2 and the tangent plane TNG0 may define an auxiliary impact angle γ₀.The auxiliary impact angle γ₀ may be e.g. in the range of 5° to 90°.Using a large auxiliary impact angle γ₀ may effectively reduce theamount of air trapped between the label 100 a and the item ITE1 a.

The tension force TF0 and/or the small radius r₀ may effectively reducethe amount of air trapped between the label 100 a and the item ITE1 a.The label 100 a tensioned by the force TF0 may temporarily have a curvedportion between the contact line CL1 and the auxiliary contact line CL2.The curved portion may have the radius r₀ of curvature. The curvedportion may be very stiff due to the high tensile modulus of the facelayer 10. The curved tensioned portion may temporarily operate as astiff reinforcing element, which may keep the contact line CL1substantially straight. The size of an air bubble may depend on theheight of a bulge formed at the contact line CL1. The size of the airbubble may be controlled by reducing the height of the bulges formed atthe contact line CL1. The curved tensioned portion may reduce the sizeof air bubbles by effectively preventing formation of bulges in thevicinity of the contact line CL1. The curved tensioned portion mayreduce the size of air bubbles by effectively preventing formation ofbulges at the contact line CL1.

The item ITE1 a may be at a position x₂ at a time t_(a,2), when thelabel 100 a is pressed against the item ITE1 a by the pressing member530 a.

Referring to FIG. 6f , the actuating unit AUNITa may be optionallyarranged to rotate the item ITE1 a about an axis AX1, so that also thetrailing edge TE2 of the label 100 a may be pressed against the itemITE1 a by a pressing member (e.g. the pressing member 530 b).Consequently, substantially the whole label 100 a may be brought intocontact with the item ITE1 a. The item ITE1 a may be moved substantiallyin the direction SX during the rotation.

The rotation of the item ITE1 a may be performed at an angular velocityω₀. The amount of air trapped between the label and the item during therotation may be reduced by rotating the items ITE1 a, ITE1 b at arelatively low angular velocity ω₀. The peel plate 510 may provide onlyone label at a time, whereas several items ITE1 a, ITE1 b may be rotatedsubstantially simultaneously. Consequently, even in high speed labeling,the angular velocity ω₀ of rotation may be arranged to be slow whencompared with the translational velocity v_(c) of the item ITE1 a. In anembodiment, the rotation of the item ITE1 a may be started e.g. afterthe leading edge FE1 of the label 100 a has been brought into contactwith the item ITE1 a.

The item ITE1 a may also be rotated e.g. by squeezing the item ITE1 abetween a first conveyor belt and a second conveyor belt, and by movingthe first and the second conveyor belts at different velocities. In thatcase, the conveyor belts may operate as the actuating unit AUNIT1 a andas the pressing members 530 a, 530 b.

The item ITE1 a may be at a position x₃ at a time t_(a,3), when thelabel 100 a is pressed against the item ITE1 a by the pressing member530 b.

Referring to FIG. 6g , the labelstock STO1 may comprise a plurality oflabels 100 a, 100 b, 100 c. A second label 100 b may be brought intocontact with a second item ITE1 b after the trailing edge TE2 of thefirst label 100 a has been separated from the release liner 90 a. Thesecond item ITE1 b may be moved e.g. by an actuator unit AUNITb.

High Speed Labeling

The apparatus 500 may be arranged to label items at a high rate. Theapparatus 500 may be arranged to attach labels to more than 750 itemsper minute. The apparatus 500 may be arranged to attach labels to itemsat a rate, which is in the range of 750 to 1600 labels per minute. Thelabeling rate of the apparatus 500 may be higher than 15 labels/second.The average velocity of the labelstock STO1 may be e.g. higher than 1m/s.

Referring to FIG. 6h , the labelstock STO1 may be sequentiallyaccelerated and decelerated e.g. more than 15 times per second. FIG. 6hshows the velocity v₁(t) of the labelstock STO1 as the function of timet. The velocity v₁(t) of the labelstock may be substantially equal tothe velocity of the surface SRF0 of a first item ITE1 when a first label100 a is brought into contact with the first item ITE1. The velocityv₁(t) of the labelstock may be temporarily reduced after the label 100 ahas been fully separated from the liner 90. A second item may be movedclose to the peel plate 510 when the velocity v₁(t) is low or zero. Thelabelstock may be accelerated again to the before the second label 100 bis brought into contact with the second item. The peak acceleration ofthe labelstock STO1 during the labeling may be e.g. higher than 2000m/s².

t_(a,−1), and t_(b,−1) may denote a time when the acceleration of thelabelstock is started. t_(a,0) and t_(b,0) may denote a time when thelabel first contacts the item. At the time t_(a,0) and t_(b,0), thevelocity v₁(t) of the labelstock may attain the velocity v_(c) of thesurface SRF0. t_(a,2) and t_(b,2) may denote a time when thedeceleration of the labelstock is started. t_(a,3) and t_(a,3) maydenote a time when the deceleration of the labelstock is stopped.

The item ITE1 a may be at a position x⁻¹ at the time t_(a,−1). The itemITE1 a may be at a position x₀ at the time t_(a,0). The item ITE1 a maybe at a position x₁ at the time t_(a,1). The item ITE1 a may be at aposition x₂ at the time t_(a,2). The item ITE1 a may be at a position x₃at the time t_(a,3). L₀₁ may denote the distance between the positionsx₀ and x₁. L₀₂ may denote the distance between the positions x₀ and x₂.L₀₃ may denote the distance between the positions x₀ and x₃.

FIG. 6i shows method steps for applying a label on the surface of anitem. The steps of FIG. 6i may be suitable for high speed labeling.

The leading edge FE1 of the label 100 a may be separated from therelease liner 90 by using a peel plate 510 (step 1210).

The leading edge FE1 of the label 100 a may be brought into contact withan item ITE1 a (step 1220).

The label 100 a may be pressed against the item ITE1 a by pressing thelabel 100 a with a pressing member 530 a (step 1230).

The trailing edge TE2 of the label may be separated from the releaseliner (step 1240).

The item ITE1 a may be optionally rotated in order to press the wholearea of the label 100 a against the item ITE1 a (step 1250). The itemITE1 a may be rotated in order to press also the trailing edge TE2 ofthe label 100 a against the item ITE1 a.

Controlling the Size of Air Bubbles

Sometimes an air bubble may be trapped between the adhesive layer andthe surface of the item. When that happens, the air bubble may causeresidual tensile stress TF1,TF2 in the face layer. The residual tensilestress TF1 of the face layer 10 may be arranged to eliminate the airbubble BUB1 by causing diffusion of air from the air bubble BUB1 throughthe face layer 10.

Also the adhesion of the adhesive layer to the surface of the item mayfacilitate elimination of air bubbles.

Referring to FIG. 7a , an air bubble (gas bubble) BUB1 may sometimes betrapped between the label and the item. REG4 may denote a region, whichcomprises an air bubble BUB1 immediately after the label has beenattached to the item ITE1. The air bubble BUB1 may be located beneath abulge of the label 100. The region REG4 may be vertically displaced withrespect to a surrounding region. The adhesive layer 20 of thesurrounding region may be in contact with the item ITE1. SRF3 may denotean interface between the adhesive layer 20 and the surface of the itemITE1. SRF4 may denote an interface between the adhesive layer 20 andair. The vertical distance between the lowermost surface of the adhesivelayer 20 and the surface SRF0 of the item ITE1 may be greater than zeroat the position of the air bubble BUB1. The distance between theinterface SRF4 and the surface SRF0 of the item ITE1 may be greater thanzero at the position of the air bubble BUB1. The thickness of the airbubble BUB1 may be e.g. greater than 0.5 μm. The adhesive layer 20 isnot in contact with the item ITE1 at the position of the air bubbleBUB1.

Referring to FIG. 7b , a residual stress of the face layer 10 and/oradhesive wetting may be arranged to cause an overpressure in the airbubble BUB1 so as to cause diffusion of air AIR1 (gas) out of the bubbleBUB1. The tension TF1, TF2 of the stiff PET face film may create anoverpressure for causing diffusion of air AIR1 out of the bubble BUB1.By selecting dispensing geometry and the stiffness of the face layer 10,the formation air bubbles may be minimized or prevented.

The adhesive may also cause wetting of the surface of the item so thatoverpressure may be generated in the bubble. The overpressure may causediffusion of air AIR1 out of the bubble BUB1. The wetting may take placeat a wetting portion WP1.

The polymeric adhesive may be a pressure sensitive adhesive. Theadhesion strength of the adhesive may develop as a function of time. Thestrength of the adhesive may increase after the label has been attachedon the substrate surface. The length of the time period needed to form asuitable strength may be called as the adhesive set-up time. Theadhesive set-up time may be e.g. longer than 30 minutes, longer than 1hour, or even longer than 24 hours. The long set-up time may facilitatewetting.

The low thickness of the polyester film 10 may increase the rate ofdiffusion of air AIR1 through the face layer 10. The permeability of theface layer 10 for air may be e.g. higher than or equal to 1 cm³/m²·24hours·100 kPa at the temperature of 25° C. The face layer 10 maycomprise or consist of polyethylene terephthalate (PET). Using PET asthe material of the face layer may provide sufficient permeability so asto control the size of air bubbles. The permeability of polyethyleneterephthalate may be higher than the permeability of polyethylenenaphthalate (PEN).

The face layer 10 may be arranged to allow diffusion or air and/ornitrogen through the face layer 10. The face layer 10 may be filmicpolyester, and the permeability of the face layer 10 for nitrogen may beequal to or higher than 1 cm³/m²×24 hours×100 kPa. The permeability maybe determined according to standard DIN 53380.

Referring to FIG. 7c , the bubbles BUB1 may be arranged to disappearafter the label has been dispensed. The method of dispensing the labelmay comprise reducing the size of air bubbles BUB1 by causing diffusionof air from the air bubble BUB1 through the face layer 10 during atleast 24 hours.

Producing the Labelstock

A labelstock STO1 may be formed of a label laminate web by die-cuttinglabels 100 and stripping excess matrix material away from the releaseliner 90, such that the labels 100 remain attached on the release liner90.

Referring to FIG. 8, a production chain for producing a labeled productPROD1 may comprise:

-   -   forming a label laminate web WEB1,    -   forming a labelstock STO1 from the label laminate web WEB1,    -   separating a printed label 100 from the labelstock STO1, and    -   attaching the printed label 100 to an item to provide a labeled        product PROD1.

Referring to FIG. 9a , label laminate web WEB0 may have an initial widthw₀. A plurality of printed regions 30 may have been formed on the facelayer 10 by printing. A plurality of printed regions 30 may have beenformed on the face layer 10 by wide web printing. The face layer 10 andthe printed regions 30 may be subsequently coated with the adhesivelayer 20 e.g. by curtain coating so as to form the label laminate webWEB0. Alternatively, the adhesive layer 20 may be formed on a releaselayer 90, and the combination of the adhesive layer 20 and release layer90 may be laminated together with the face layer 10.

The label laminate web WEB0 may be longitudinally cut to form a narrowerlabel laminate web WEB1. The web WEB0 may be cut e.g. along alongitudinal line CUT0. The web may have a width w₁. The width w₁ may besmaller than the width initial width w₀.

Referring to FIG. 9b , the label laminate web WEB1 may comprise the facelayer 10, the adhesive layer 20, and one or more printed regions 30. Thelabel laminate web WEB1 may further comprise a release liner 90. Therelease liner 90 may be coated with a release coating 91. The releaseliner 90 may have a thickness d₉₀.

Referring to FIG. 9c , individual labels 100 a, 100 b may be cut fromthe web WEB1 e.g. by using a die-cutting blade DIE1 and a base BED0. Thecutting edge of the blade DIE1 may penetrate through the face layer 10and through the adhesive layer 20. The cutting edge of the blade DIE1may also slightly penetrate into the release liner 90. Advantageously,the blade DIE1 does not cut completely through the release liner 90. Alabelstock STO1 may be formed from the web WEB1 e.g. by the die-cutting.

The thickness of the d₉₀ of the release liner 90 may be selected tofacilitate precision die-cutting. In particular, the release liner 90may comprise dimensionally stable and relatively hard polyester in orderto allow precision cutting. The release liner 90 may comprise polyesterin order to allow precision cutting.

Referring to FIG. 9d , the labelstock STO1 may comprise a plurality oflabels 100 a, 100 b, 100 c carried by a common release liner 90.

FIG. 9e shows method steps for forming the labelstock STO1 and labelingitems with the labels of the labelstock.

In step 810, the face layer may be printed to form the printed regions30. The printed regions 30 may comprise markings MRK1.

In step 820, the printed face layer may be coated with the adhesive. Theadhesive layer may comprise one or more adhesive sub-layers.

In step 830, the combination of the face layer 10 and the adhesive layer20 may be laminated with a release layer in order to form label laminateweb WEB0.

In step 840, one or more narrower webs WEB1 may be cut from the webWEB0.

In step 850, the labels may be cut e.g. by die-cutting. Labelstock STO1may be formed from the web WEB1 by die-cutting.

In step 860, the labelstock STO1 may be stored and/or transported.

In step 870, the labels 100 a,100 b, 100 c of the labelstock STO1 may beattached to items, so as to provide labeled items PROD1.

Referring to FIGS. 10a to 10d , the label 100 or labels 100 a,100 b, 100c may also be provided as linerless labels. The linerless labels may besupplied e.g. as a stack (i.e. a pile) or as a roll RLL1. The uppersurface of the face layer 10 may be coated with a release coating 91, soas to facilitate separation of the labels from each other. Referring toFIGS. 10c and 10d , a first label 100 a may be separated from a secondadjacent label 100 b e.g. by cutting or tearing the labels apart along aline CUT1.

Referring to FIG. 11a , the label laminate web may also be formed e.g.by providing a base film (step 910), and coating the base film by arelease coating 91 in order to form the release layer 90 (step 920). Theadhesive layer 20 may be applied on the release layer 90 e.g. by curtaincoating (step 930). The printed face layer 30 may be subsequentlyapplied on top of the adhesive layer 20 in order to form the labellaminate web WEB0, WEB1 (step 940). The label laminate web WEB0, WEB1may be optionally topcoated (step 950). The labels 100 a, 100 b, 100 cmay be cut from the face layer 10 in step 960.

Referring to FIG. 11b , the supply chain may utilize various resourcesfor providing and using labeled items. For example, a press manufacturermay provide a printing machine for forming the printed regions 30(resource 1010). An ink provider may provide printing ink for formingthe printed regions 30 (resource 1020). The regions 30 may be formed onthe face layer 10 by using a printing machine (resource 1030). thelabels 100 a, 100 b may be cut by using die-cutting apparatus (resource1040). The labels may be attached to items by using a labeling apparatus500 (resource 1050). The supply chain may utilize contribution frombrand owners (resource 1060), contribution from distributors (resource1070). The labeled items may be delivered to end users (resource 1080).The list of FIG. 11b is non-exhaustive.

Tensile Strength

The tensile strength σ₁₀ of the polyester film may be e.g. higher thanor equal to 140 MPa. The polyester film may be bi-axially oriented, andthe tensile strength of the polyester film may be e.g. higher than orequal to 140 MPa in the machine direction (MD), and the tensile strengthof the polyester film may be e.g. higher than or equal to 140 MPa in thecross direction (CD).

The tensile strength (σ₁₀) of the polyester film face layer (at break)may be equal to or higher than 200 MPa. The face layer may be uniaxiallyor biaxially oriented. When the polyester film is bi-axially oriented,the tensile strength of the polyester film may be similar in bothmachine direction and cross direction higher. The face layer 10 may bemade of a PET film. The tensile strength of the PET film (at break) maybe e.g. than higher than or equal to 200 MPa in the machine direction(MD), and the tensile strength of the polyester film at break may behigher than or equal to 200 MPa in the cross direction (CD). The tensilestrength of the PET film may be e.g. than higher than or equal to 220MPa (32000 psi) in the machine direction (MD), and the tensile strengthof the polyester film may be higher than or equal to 220 MPa (32000 psi)in the cross direction (CD). The tensile strength may be determinedaccording to standard ASTM D 882.

Ultimate Elongation

The ultimate elongation of the polyester film face layer may be in therange of 65 to 190%. For example, the ultimate elongation of thepolyester film face layer may be higher than or equal to 110%. The facelayer may comprise or consist of bi-axially oriented PET film, whereinthe elongation of the PET film may be e.g. higher than or equal to 140%in the machine direction (MD), and the elongation of the PET film may bee.g. higher than or equal to 140% in the cross direction (CD). Theultimate elongation may be determined according to standard ASTM D 882.

Degree of Crystallization

The face layer 10 may comprise semi-crystalline polymeric film. Thedegree of crystallization may have an effect on optical, mechanical,thermal and chemical properties of the polymer. The degree ofcrystallization of the semi-crystalline polymeric film may be in therange of 10% to 80%. The polymeric film may be oriented by uniaxial orbiaxial stretching. The stretching may increase elastic modulus and/orrefractive index of the face layer 10.

UV Protection

In an embodiment, the face layer 10 may protect the printed region 30from ultraviolet radiation (UV). For example, sunlight may comprise UVradiation. The UV radiation may bleach the color of the printed region30. The face layer 10 may optionally comprise an additive, which mayabsorb UV radiation. The face layer may be substantially transparent inthe wavelength range of 380 nm to 760 nm, wherein the face layer mayabsorb UV radiation in the UV range.

The face layer 10 may protect the printed region 30 against thebleaching effect of sunlight.

Tendency to Build Up Static Charge

Filmic polyester may have a tendency to build up static electric charge.Reducing the thickness of the face layer may provide a label, which hasa reduced tendency to build up static electric charge.

Adhesive Dispersion

Producing the label may comprise applying an adhesive dispersion on theface layer 10 or on the release layer 90. The adhesive layer 20 may beproduced by applying the adhesive dispersion on the face layer 10 or onthe release layer 90. The dispersion may have low viscosity value. Thelow viscosity may facilitate forming a substantially uniform thicknessof the adhesive layer 20. The low viscosity may facilitate forming asubstantially uniform thickness of the label 100. The polymeric adhesivemay be applied, for example by curtain coating. The exposed surface ofthe adhesive may be optionally leveled e.g. by a linear smoothing bar.The thickness of the printed region may be non-negligible. The lowviscosity may facilitate eliminating an elevated region, which could becaused by the thickness of the printed region 30.

The viscosity of the polymeric adhesive may be equal to or less than2000 centipoises, preferably lower than 1600 centipoises. The viscosityof the polymeric adhesive may be, for example, in the range of 1200 to1600 centipoises, when measured with a Brookfield RVT Viscometer with #3spindle at 20 rotations per minute (rpm) according to the manufacturer'sinstructions. One centipoise corresponds to one mPa×s in SI-units.

The adhesive dispersion may be applied on the semi-crystalline polymericfilm such that the polymeric film does not absorb the adhesivedispersion to a significant degree.

Temperature Range

The service temperature range of the polymeric adhesive of the label 100may comprise e.g. the range of −60° F. to 300° F. (−51° C. to 149° C.).The service temperature range of the polymeric adhesive may comprisee.g. the range of −40° F. to 200° F. (−40° C. to 93° C.).

The label may be applied to the item e.g. at a temperature, which ishigher than or equal to 23° F. (5° C.).

SX, SY, and SZ denote orthogonal directions.

For the person skilled in the art, it will be clear that modificationsand variations of the labels, products and the methods according to thepresent invention are perceivable. The figures are schematic. Theparticular embodiments described above with reference to theaccompanying drawings are illustrative only and not meant to limit thescope of the invention, which is defined by the appended claims.

What is claimed is:
 1. A label, comprising: a face layer, and anadhesive layer, wherein the face layer comprises semi-crystallinepolymeric film, the adhesive layer consists of one or more adhesivesub-layers, a lowermost adhesive sub-layer of said adhesive sub-layerscomprises transparent polymeric adhesive, the thickness of the facelayer is in the range of 10 μm to 50 μm, the thickness of the adhesivelayer is in the range of 8 μm to 25 μm, the thickness of the adhesivelayer is smaller than 95% of the thickness of the face layer, anuppermost sub-layer of said adhesive sub-layers is in contact with theface layer, and the refractive index of the uppermost adhesive sub-layeris in the range of 80% to 98.5% of the refractive index of thesemi-crystalline polymeric film.
 2. The label of claim 1, wherein thetotal thickness of the label is in the range of 150% to 195% of thethickness of the face layer, the total thickness of the label being thethickness from the uppermost surface of the face layer to the lowermostsurface of the lowermost adhesive sub-layer.
 3. The label of claim 1,wherein semi-crystalline polymeric film is a polyester film.
 4. Thelabel of claim 3, wherein the polyester film is polyethyleneterephthalate film.
 5. The label of claim 4, wherein the permeability ofthe face layer for air is higher than or equal to 1 cm³/m²·24 hours·100kPa at the temperature of 25° C.
 6. The label of claim 3, wherein thetensile modulus of the face layer is higher than or equal to 4000 MPa inthe machine direction.
 7. The label of claim 3, wherein the polyesterfilm is bi-axially oriented, and the tensile strength of the polyesterfilm is higher than or equal to 200 MPa in the machine direction, andthe tensile strength of the polyester film is higher than or equal to200 MPa in the cross direction.
 8. The label of claim 3, wherein thehardness of the face layer is higher than 94 in the Rockwell M scale. 9.The label of claim 1, wherein the polymeric adhesive comprises anacrylic emulsion polymer.
 10. The label of claim 1, wherein the surfacetension of the polymeric adhesive is lower than or equal to 40 dyn/cm atthe temperature of 25° C.
 11. The label of claim 1, wherein theadvancing contact angle for wetting a polyethylene terephthalate surfacewith the polymeric adhesive is lower than 70° at the temperature of 25°C.
 12. The label of claim 1, wherein the uppermost surface of the labelhas been coated with a release coating.
 13. The label of claim 1,wherein the label is attached to a release liner such that the adhesivelayer is between the face layer and the release liner.
 14. The label ofclaim 13 wherein the release liner comprises polyester.
 15. The label ofclaim 13, wherein the label is carried by the release layer, and therelease value of the label is higher than 0.15 N in a situation where asample piece of the label is separated from the release liner at anangle of 180° at a velocity of 1200 inches per minute at the temperatureof 25° C., the width of said sample piece being equal to 2 inches. 16.The label of claim 1, wherein the refractive index of the polyester filmis in the range of 1.55 to 1.65 at the wavelength of 550 nm.
 17. Thelabel of claim 1, wherein the face layer has been stretched so that therefractive index of the face layer is higher than 1.60.
 18. The label ofclaim 1 comprising a printed region.
 19. The label of claim 18, whereinthe printed region has been implemented between the face layer and theadhesive layer.
 20. The label of claim 1, wherein the haze level of thepolyester film is lower than or equal to 6.5%.
 21. The label of claim18, wherein the shape of the perimeter of the printed region of thelabel is substantially different from the shape of the perimeter of thelabel.
 22. A labeled item, comprising a label attached to the surface ofthe item, said label comprising: a face layer, and an adhesive layer,wherein the face layer comprises semi-crystalline polymeric film, theadhesive layer consists of one or more adhesive sub-layers, a lowermostadhesive sub-layer of said adhesive sub-layers comprises transparentpolymeric adhesive, the thickness of the face layer is in the range of10 μm to 50 μm, the thickness of the adhesive layer is in the range of 8μm to 25 μm, the thickness of the adhesive layer is smaller than 95% ofthickness of the face layer, an uppermost sub-layer of said adhesivesub-layers is in contact with the face layer, and the refractive indexof the uppermost adhesive sub-layer is in the range of 80% to 98.5% ofthe refractive index of the semi-crystalline polymeric film.
 23. Thelabeled item of claim 22, wherein the surface of the item has a firstreflection coefficient, a labeled portion of the labeled item has asecond reflection coefficient, and the relative difference between thefirst reflection coefficient and the second reflection coefficient issmaller than 20%.
 24. The labeled item of claim 22, wherein an interfacebetween the face layer and the adhesive layer has a reflectioncoefficient, the uppermost layer of the label has a reflectioncoefficient, and the reflection coefficient of the interface is smallerthan 10% of the reflection coefficient of the uppermost layer.
 25. Thelabeled item of claim 22, wherein the surface roughness value of thesurface is in the range of 0.5 μm to 5 μm.
 26. The labeled item of claim22, wherein the label comprises a printed region between the face layerand the adhesive layer, and the distance between the printed region andthe surface of the item is in the range of 50% to 95% of the thicknessof the face layer.
 27. The labeled item of claim 22, wherein the item isa transparent container made of glass.
 28. The labeled item of claim 22,wherein the item is a transparent container made of polyethyleneterephthalate.
 29. The labeled item of claim 22, wherein the uppermostsurface of the label comprises silicone polymer.
 30. The labeled item ofclaim 22, wherein the label comprises a clear portion to transmitilluminating light to the surface of the item and to transmit reflectedlight from the surface of the item to the eye of a viewer.
 31. A methodfor labeling items, the method comprising: separating a label from arelease liner by using peel plate, moving the surface of an item in afirst direction, moving the label in a second direction, and bringing aleading edge of the label into contact with a surface of the item suchthat the angle between the first direction and the second direction isin the range of 10° to 30°, wherein the label comprises: a face layer,and an adhesive layer, wherein the face layer comprises semi-crystallinepolymeric film, the adhesive layer consists of one or more adhesivesub-layers, a lowermost adhesive sub-layer of said adhesive sub-layerscomprises transparent polymeric adhesive, the thickness of the facelayer is in the range of 10 μm to 50 μm, the thickness of the adhesivelayer is in the range of 8 μm to 25 μm, and the thickness of theadhesive layer is smaller than 95% of thickness of the face layer. 32.The method of claim 31, wherein the semi-crystalline polymeric film is apolyester film.
 33. The label of claim 31, wherein the polymericadhesive comprises an acrylic emulsion polymer.
 34. The method of 33,wherein the release value of the combination of the label and therelease liner is higher than 0.15 N in a situation where a sample pieceof the label is separated from the release liner at an angle of 180° ata velocity of 1200 inches per minute at the temperature of 25° C., thewidth of said sample piece being equal to 2 inches.
 35. The method ofclaim 31, wherein the maximum velocity of the release liner is higherthan 1 m/s such that the rate of labeling is higher than 1000 items perminute.
 36. The method of claim 31, wherein the velocity of the releaseliner is temporarily reduced between labeling a first item and labelinga second item.
 37. The method of claim 31, comprising controllingentrainment of air to an interface between the label and the item bycausing longitudinal tension in the label when the leading edge of thelabel is in contact with the item and when a trailing edge of the labelis still in contact with the release liner.
 38. The method of claim 31,wherein the material of the lowermost adhesive sub-layer has beenselected to pressurize an air bubble trapped between the label and theitem, so as to cause diffusion of air through the face layer of thelabel.
 39. The method of claim 31, wherein the semi-crystallinepolymeric film is a polyester film, and the permeability of thepolyester film for air at 25° C. is higher than or equal to 1 cm³/m²·24hours·100 kPa.
 40. The method of claim 31, wherein an air bubble isformed between the label and the item, and a residual stress of the facelayer is arranged to remove the air bubble by causing diffusion of airfrom the air bubble through the face layer.
 41. The method of claim 31,comprising reducing the size of air bubbles by causing diffusion of airfrom the air bubble through the face layer during at least 24 hours. 42.The method of claim 31, wherein the radius of curvature of the item issmaller than 50 mm.
 43. The method of claim 31, comprising pressing thelabel by a pressing member such that a portion of the label istemporarily bent, wherein the radius of curvature of the bent portion ofthe label is smaller than 10 mm.